1. Field of the Invention
This invention relates to a vent valve used in a fuel tank for venting vapor, shutting off fluid flow when the fuel tank is in an overfill condition and preventing fuel leakage in the event of a rollover.
2. Description of Related Art
Fuel tanks, and more particularly vehicle/automobile fuel tanks are subject to a great deal of scrutiny during the design phase. Fuel tanks are formed in complex forming operations involving numerous layers of material that may lose integrity when layer continuity is interrupted. One such interruption takes place when a sending unit is positioned within a sidewall of the fuel tank. The sending unit includes electronics and diagnostics for the operation of the vehicle including a fuel level gauge and/or a fuel pump.
In addition, vent valves are commonly used in fuel tanks to vent excess vapor from an interior of the fuel tank to an exterior of the fuel tank, usually to an external filter. Existing vent valves are primarily rigidly fixed through a sidewall of the fuel tank and comprise a float, spring and flapper valve in an arrangement similar to that shown in U.S. Pat. No. 4,960,153. Such existing vent valves require an interface with the fuel tank in addition to the interface created by the sending unit. These interfaces may become prone to corrosion, leakage and/or other factors that may compromise the safety and integrity of the vehicle.
Fuel within fuel tanks releases vapors that may be harmful to the environment and create a safety hazard to the occupants of the vehicle. Fuel tanks typically include sending units that are positioned within a sidewall of the fuel tank and contain electronics and diagnostics related to the operation and maintenance of the vehicle.
A vent valve according to a preferred embodiment of this invention is positioned within the fuel and is tethered to a sidewall of the fuel tank, preferably through the existing sending unit. The vent valve is designed to vent fuel vapors from an interior of a fuel tank through a vent hose that extends through the sending unit and ultimately to the exterior of fuel tank, such as to a charcoal filter.
A floating body is preferably incorporated into the vent valve and comprises a buoyant material. A valve is preferably positioned within the floating body. The valve is positioned to open and close depending upon an internal pressure of the fuel tank and/or a level of fuel within the fuel tank and/or a relative position of fuel within the fuel tank.
A vent is preferably positioned with respect to the floating body and further arranged in fluid communication with the valve. The vent preferably creates an outlet for vapor from the vent valve. A vent hose is further positioned with respect to the vent and forms a vapor path from the valve to an exterior of the fuel tank.
The valve may include a valve float having an internally positioned valve channel. The valve float is preferably rotatably positioned within the floating body so that the valve channel within the valve float and correspondingly rotates relative to the floating body. The valve channel is sized to permit vapor to escape through the vent valve but prevent the free flow of fluid through the vent valve.
A check valve is preferably positioned relative to the vent and may include two O-rings positioned to flex and permit either the entry of vapor or the exit of vapor from within the vent valve. The vapor is thereupon directed through the vent hose and to the exterior of the fuel tank. The check valve preferably permits a two way exchange of pressure between the interior and exterior of the fuel tank.
The floating body preferably includes a plurality of channels positioned between the floating body and the valve. In addition, the valve and/or the floating body may include a plurality of baffles to permit passage of vapor from an exterior of the vent valve to an interior of the vent valve.
It is one object of this invention to provide a buoyant vent valve that vents vapor from a fuel tank through a vent hose that passes through a sending unit in a sidewall of the fuel tank.
It is another object of this invention to provide a buoyant vent valve that provides a vent for a fuel tank.
It is another object of this invention to provide a buoyant vent valve that maintains a predetermined pressure range within the fuel tank.
It is yet another object of this invention to provide a buoyant vent valve that will operate across a wide range of temperatures.
It is still another object of this invention to provide a buoyant vent valve that will not allow any fuel to escape from the fuel tank in the event of a rollover or extreme inclination.
It is yet another object of this invention to provide a buoyant vent valve that shuts off all flow when the fuel tank is in an overfill condition.
It is still another object of this invention to provide a buoyant vent valve that works in any orientation and does not require mounting holes in the fuel tank.